Plane multi-digit type electric discharge display devices

ABSTRACT

In a plane multi-digit type electric discharge device of the class comprising an insulator substrate, a plurality of pattern display units arranged in side-by-side relationship on the insulator substrate, each display unit including a plurality of segment electrodes which are arranged in a predetermined pattern, a plurality of electrically isolated counter electrodes respectively confronting the pattern display units, an upper substrate, at least the portions thereof confronting the pattern display units being transparent, and a common envelope containing above described component elements, there are provided a discharge sustaining electrode near the pattern display unit at the end from which scanning is to be commenced and a counter electrode confronting the discharge sustaining electrode thereby constantly sustaining an electric discharge between the discharge sustaining electrode and the last mentioned counter electrode. Further a coating of a radioactive substance is located near the discharge sustaining electrode for supplying thereto a sufficient quantity of electrons for initiating a discharge.

United States Patent [191 Kohyama et al.

[451 Dec. 31, 1974 PLANE MULTI-DIGIT TYPE ELECTRIC DISCHARGE DISPLAY DEVICES [73] Assignee: Hitachi, Ltd., Tokyo, Japan [22] Filed: Oct. 6, 1972 [21] Appl. No.: 295,550

[30] Foreign Application Priority Data Oct. 6, 1971 Japan 46-77873 [52] U.S. Cl. 313/54, 313/1095 [51] Int. Cl. H0lj 7/40 [58] Field of Search 313/54, 109.5

[56] References Cited UNITED STATES PATENTS 3,480,820 11/1969 Fehnel 313/1095 Primary Examinerl-Ierman Karl Saalbach Assistant Examiner-Darwin R. Hostetter Attorney, Agent, or FirmDike, Bronstein, Roberts, Cushman & Pfund 5 7 ABSTRACT In a plane multi-digit type electric discharge device of the class comprising an insulator substrate, a plurality of pattern display units arranged in side-by-side relationship on the insulator substrate, each display unit including a plurality of segment electrodes which are arranged in a predetermined pattern, a plurality of electrically isolated counter electrodes respectively confronting the pattern display units, an upper substrate, at least the portions thereof confronting the pattern display units being transparent, and a common envelope containing above described component elements, there are provided a discharge sustaining electrode near the pattern display unit at the end from which scanning is to be commenced and a counter electrode confronting the discharge sustaining elec trode thereby constantly sustaining an electric discharge between the discharge sustaining electrode and the last mentioned counter electrode. Further a coating of a radioactive substance is located near the discharge sustaining electrode for supplying thereto a sufficient quantity of electrons for initiating a discharge.

6 Claims, 2 Drawing Figures PLANE MULTI-DIGIT TYPE ELECTRIC DISCHARGE DISPLAY DEVICES BACKGROUND OF THE INVENTION This invention relates to a plane multi-digit type electric discharge display device, and more particularly to such display device in which the delay of the initial discharge is minimized and the build-up of the discharge caused by a driving pulse is improved.

In the conventional plane multi-digit type electric discharge display device there are provided a plurality of display discharge tubes which are arranged side-byside relationship. As the display discharge tube has generally been used a so-called NIXIE (trade mark) tube wherein a plurality of cathode electrodes corresponding to a desired pattern are disposed along a line perpendicular to the tube axis and wherein a voltage is impressed across a selected cathode electrode and an anode electrode to cause the selected cathode electrode to establish a glow discharge whereby to display a pattern. In such a multi-digit type discharge display device a color filter or the like has been placed in front of the display apparatus for the purpose of decreasing the internal reflection of external lights as well as the halation from adjacent NIXIE (trade mark) tubes.

However, with such a multi-digit type discharge dis play apparatus, since the external lights are intercepted by the filter, it is difficult to utilize a sufficient number of initial electrons necessary to initiate the discharge so that it takes several tens seconds before commencement of the discharge. Especially when the display device is used in dark spaces such as rooms, extremely long time ranging from several tens seconds to several minutes is required before the discharge commences.

To solve this problem it has been proposed to introduce such radioactive substances as Ni, "Pr and H, for example, into each one of a plurality of NIXIE (trade mark) tubes comprising the multi-digit type discharge display device or to provide for the NIXIE (trade mark) tubes electrodes that can normally sustain the discharge, such electrodes being called keep alive electrodes." Such a solution, however, is not advantageous in that a large amount of labor is required to introduce the radioactive substances in respective NIXIE (trade mark) tubes and that in a tube using a large number of digits the quantity of the radioactive substance introduced often exceeds a limit prescribed by a law. Moreover, where the keep alive electrode is used the light emitted by the discharge of the keep alive electrode of one tube reflects at the envelopes of adjacent tubes thus obscuring the displayed pattern. Moreover such a keep alive electrode increases the power consumption of the multi-digit discharge display device because it always sustains discharge. Further, the physical size of the display apparatus is increased because the keep alive electrode is provided for each tube.

SUMMARY OF THE INVENTION It is an object of this invention to provide an improved plane multi-digit type discharge display device capable of eliminating the time lag of the discharge at the pattern display unit at one end from which the scanning is to be commenced thereby preventing the pattern displayed at this display unit from becoming obscure.

Another object of this invention is to provide an improved plane multi-digit type discharge display device capable of instantaneously displaying a desired pattern without any delay of discharge even when voltage is initially applied in the dark.

Still another object of this invention is to provide an improved plane multi-digit type discharge display device of extremely low power consumption.

According to the invention there is provided a plane multi-digit type electric discharge device of the class comprising an insulator substrate, a plurality of pattern display units arranged side-by-side relationship on the insulator substrate, each display unit including a plurality of segment electrodes which are arranged in a predetermined pattern, a plurality of electrically isolated counter electrodes respectively confronting the pattern display units, an upper substrate, at least the portions thereof confronting the pattern display units being transparent, and a common envelope containing above described component elements, characterized in that there are provided a discharge sustaining electrode near the pattern display unit at the end from which scanning is to be commenced and a counter electrode confronting the discharge sustaining electrode thereby constantly sustaining an electric discharge between the discharge sustaining electrode and the last mentioned counter electrode.

According to another aspect of this invention there is provided a coating of a radioactive substance near the discharge sustaining electrode for preventing the delay of discharge.

BRIEF DESCRIPTION OF THE DRAWINGS Further objects and advantages of the invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 7

FIG. 1 shows a front elevation of one embodiment of the novel plane multi-digit type electric discharge display device and FIG. 2 is an exploded perspective view of various component elements of the display device shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT According to this invention, there is provided a plane multi-digit type electric discharge display device which comprises a plurality of juxtaposed display units, each including a plurality of segment electrodes which are disposed in the shape of a figure 8 or a criss-cross bounded by a square. In the preferred embodiment shown in the drawing ten such display units are used. The plane multi-digit type discharge display device 1 comprises a flat rectangular insulator substrate 2 of ceramic, for example, a spacer 3 formed by a plate shaped insulator of ceramic, for example, electrically isolated discrete counter electrodes 4a through 4k of metal wire net, for example, and a transparent upper substrate 5 of glass or the like. On the upper surface of the insulator substrate 2 are arranged in a side-by-side relationship a plurality of pattern display units 7a through 7j, each including a plurality of segment electrodes 6 which are arranged in the form of a figure 8 or a criss-cross bounded by a square. Corresponding ones of the segment electrodes of respective display units are commonly connected to conductors 8a through 8i which are connected to external terminals 9a through 9i on one end of the substrate 2. Near the first digit of the pattern display units 7a through 7 j on the insulator substrate 2, that is at the righthand end thereof is provided a discharge sustaining electrode 10 which is connected to an external terminal 9i via conductor 8i. Advantageously, the segment electrodes 6 and the discharge sustaining electrode 10 are made of metal which is difficult to be sputtered such as molybdenum, tungsten, tantalum or their alloys, whereas conductors 8a through 8i and external terminals are made of highly conductive metal such as silver or the like. The upper surface of the insulator substrate 2 except the segment electrodes 6, the discharge sustaining electrode l and external terminals 9a through 9i is covered by an insulator layer 11 for the purpose of preventing an abnormal discharge. The spacer 3 takes the form of a flat rectangular plate like the insulator substrate 2 and spacer 3 is provided with a plurality of windows 12 corresponding to the pattern display units 7a through 7j and the discharge sustaining electrode 10, the windows being formed by any well known process such as photoetching or ultra-sonic machining process. A coating 13 of a radioactive isomer is applied to the righthand end of the spacer 3 near the first digit or the discharge sustaining electrode 10.

The component elements described above are superposed one upon the other to form a lamination such that the pattern display units 7a through 7] and the discharge sustaining electrode align with respective windows 12 of the spacer and with the counter electrodes 4a through 4k. The periphery of the lamination is hermetically sealed with frit glass, for example, to complete a sealed envelope which is then evacuated and filled with a luminous inert gas such as neon gas or argon gas.

In operation, a voltage is normally impressed across the discharge sustaining electrode 10 and the counter electrode 4k through the external terminal 9i thus constantly sustaining a discharge between these electrodes. Then, one of the external terminals 9a through 9k corresponding to the desired pattern is selected and a voltage is applied to the selected external terminal and to.

a corresponding counter electrode whereby a selected segment electrode 6 luminescences to display the desired pattern. By sequentially selecting the pattern display units 70 through 7j starting from the unit 7a on the time division basis it is possible to display all digits substantially simultaneously.

Different from the well known multi-digit type discharge display device in which anum'ber of above described NlXlE tubes are arranged side-by-side relationship, that is respective digits are sealed in independent envelopes, in the novel display device all digits or display units are contained in a common envelope filled with a luminous inert gas so that whenever any one of the segment electrodes commences to discharge by the presence of initial electrons, this segment electrode sequentially supplied electrons to adjacent segment electrodes in a quantity sufficient to establish discharges, thereby assuring instantaneous discharge of all digits. As above described the multi-digit type discharge display device is generally operated on the time division basis wherein the display units are sequentially operated starting from the first digit (the righthand digit in this example). With the novel display device even when a signal is applied that renders OFF the voltage on the first digit and ON the voltage on the second digit, after establishment of the discharge at the first digit or pattern display unit 7a, as the first digit supplies to the second digit electrons of the quantity sufficient to establish the discharge, the second digit or display unit commences to discharge substantially simultaneously with the application of voltage thereon. The next and succeeding digits commence to discharge in the same manner. When the last digit (the lefthand display unit 7 in this example) is reached, the operation is repeated starting from the first digit. As the distance between the last digit 7 j and the first digit 7a increases with the number of the digits, and the first digit will not be supplied with electrons of sufficient quantity. As a consequence, the discharge of the first digit is delayed thereby obscuring its display. However, according to this invention, since the discharge sustaining electrode 10 that constantly sustains discharge is located near the first digit or display unit 7a, the first digit can operate concurrently with the application of voltage thereon by the constant supply of electrons-from the nearby discharge sustaining electrode 10 of a quantity sufficient to assure instantaneous discharge.

When voltage is firstly applied to the novel display apparatus in the dark since any discharge is not yet established at the discharge sustaining electrode 10, the commencement of the discharges at respective pattern display units 7a through 7] might be delayed. However, according to this invention, because a radioactive substance 13 is disposed near the end from which the scanning is to be commenced, that is the first pattern display unit 70, this unit commences discharge substantially concurrently with the application of the operating voltage thereon since the radioactive substance supplies to the display unit 7a electrons of a quantity sufficient to establish discharge. Thereafter, succeeding pattern display units 7b through 7j are operated sequentially in the same manner as above described, thus displaying all digits substantially instantaneously.

Although in the above illustrate embodiment, the counter electrodes are shown as metal wire nets these electrodes can take any other forms such as Nesa glass (trade mark) which is a transparent glass plate coated with transparent conductive substance.

As above described, this invention provides a 'new and improved plane multi-digit type discharge display device wherein all display units or digits are contained in a common flat envelope filled with a discharge medium, and a discharge sustaining electrode that constantly sustains discharge and a counter electrode cooperating therewith are provided near the pattern display unit at the end from which the scanning is to be commenced thereby eliminating the delay of the discharge and preventing the displayed pattern from becoming obscure. Further, in the novel display device, since a radioactive substance is disposed near the discharge sustaining electrode even when an operating voltage is impressed upon the display device in the dark, electrons of the quantity sufficient to commence to discharge are supplied to the discharge sustaining electrode and nearby display unit from the radioactive substance thereby eliminating any delay of the discharge thus assuring instantaneous and simultaneous display of all patterns.

Different from the conventional multi-digit type display device in which a plurality of Nixy tubes, each including a discharge sustaining electrode, are arranged side-by-side relationship it is possible to greatly reduce the power consumption because only one discharge sustaining electrode is used in common for all display units which are contained in a single common envelope. Further, provision of the discharge sustaining electrode at the end from which scanning is to be commenced is especially advantageous for the socalled zero suppress system in which unwanted digits are not operated.

What is claimed is:

l. A plane scanning multi-digit type electric discharge display device comprising an insulator substrate, a plurality of pattern display units arranged sideby-side relationship on said insulator substrate, each display unit including a plurality of segment electrodes which are arranged in a predetermined pattern, a plurality of electrically isolated counter electrodes respectively confronting said pattern display units, and an upper substrate, at least the portions of said counter electrodes and said upper substrate confronting said pattern display units being transparent, and a common envelope containing pattern display units, and a single discharge sustaining electrode adapted for constantly discharging and located near an end pattern display unit at the end from which scanning is to be commenced.

2. The plane multi-digit type electric discharge display apparatus as claimed in claim 1 wherein a radioactive substance is provided near said discharge sustaining electrode thereby preventing the delay of discharge at the commencement of discharge.

3. The plane multi-digit type electric discharge display apparatus as claimed in claim 1 wherein a spacer is interposed between said insulator substrate and said counter electrodes, said spacer being provided with windows at portions corresponding to said pattern display units and said discharge sustaining electrode.

4. The plane multi-digit type electric discharge display device as claimed in claim 1 wherein said discharge sustaining electrode is mounted upon said insulator substrate.

5. The plane multi-digit type electric discharge display device as claimed in claim 1 wherein said counter electrodes comprise metal wire nets.

6. The plane multi-digit type electric discharge display device as claimed in claim 1 wherein said counter electrodes comprise transparent electroconductive 

1. A plane scanning multi-digit type electric discharge display device comprising an insuLator substrate, a plurality of pattern display units arranged side-by-side relationship on said insulator substrate, each display unit including a plurality of segment electrodes which are arranged in a predetermined pattern, a plurality of electrically isolated counter electrodes respectively confronting said pattern display units, and an upper substrate, at least the portions of said counter electrodes and said upper substrate confronting said pattern display units being transparent, and a common envelope containing pattern display units, and a single discharge sustaining electrode adapted for constantly discharging and located near an end pattern display unit at the end from which scanning is to be commenced.
 2. The plane multi-digit type electric discharge display apparatus as claimed in claim 1 wherein a radioactive substance is provided near said discharge sustaining electrode thereby preventing the delay of discharge at the commencement of discharge.
 3. The plane multi-digit type electric discharge display apparatus as claimed in claim 1 wherein a spacer is interposed between said insulator substrate and said counter electrodes, said spacer being provided with windows at portions corresponding to said pattern display units and said discharge sustaining electrode.
 4. The plane multi-digit type electric discharge display device as claimed in claim 1 wherein said discharge sustaining electrode is mounted upon said insulator substrate.
 5. The plane multi-digit type electric discharge display device as claimed in claim 1 wherein said counter electrodes comprise metal wire nets.
 6. The plane multi-digit type electric discharge display device as claimed in claim 1 wherein said counter electrodes comprise transparent electroconductive plates. 